This invention relates to an apparatus for attachment to a pipe handling arm and to a method of handling tubular.
Pipe handling apparatus generally comprises a pipe handling arm and a clamp. The pipe handling arm is fixed at one end to a derrick or to a rig floor of a drilling rig. The other end of the pipe handling arm is free to move in at least one plane, and usually two or three planes. The clamp is attached to the free end of the pipe handling arm. In use, the free end of the pipe handling arm is swung over to a pipe rack. The clamp clamps on to a tubular and then picks the tubular up and manoeuvres it into a position generally over an upper section of a tubular string at the well centre. Typically the tubulars are not in perfect alignment due to tolerance in the pipe handling arm. In order to ensure correct alignment a stabbing guide is then strapped around the threaded box of the upper section of the tubular string. The threaded pin of the tubular is then lowered into the threaded box of the upper section of the tubular string, and is guided into alignment therewith by the stabbing guide.
Although it only takes a relatively short time to mount and remove a stabbing guide it would be desirable to reduce this time because of the high costs associated with the running of a drilling rig.
U.S. Pat. No. 4,625,796 discloses a system for aligning tubulars in which the tubular to be connected is transferred to two jaws mounted on a derrick via parallel arms.
U.S. Pat. No. 4,650,235 discloses an attachment for a pipe handling arm where a tubular is allowed to move through centering jaws.
The present invention provides an apparatus for attachment to a pipe handling arm, comprising a clamp for gripping a tubular and a guide for aligning said tubular with another tubular prior to connection thereof, characterised in that said clamp and said guide are movable relative to each other in a direction longitudinal of the tubular, the arrangement being such that said tubular can be brought closer to said another tubular in a direction longitudinal of the tubular.
The tubulars could be casing, liner or other type of pipe and especially large diameter tubulars, for example 36xe2x80x3 casing.
Preferably, said clamp and said guide arranged on a strut.
Advantageously, at least one of said clamp and said guide is moveable along said strut by a hydraulic piston and cylinder.
Alternatively, at least one of said clamp and said guide is movable along said strut by a pneumatic piston and cylinder.
Preferably, said strut is divided into a first portion and a second portion and said second portion is offset from said first portion.
Advantageously, said apparatus further comprises a second clamp which is in a fixed relation to said clamp.
Preferably, said clamp(s) comprise jaws movable between an open and a closed position.
Advantageously, said apparatus further comprises a hydraulic piston to move said jaws between their open and closed positions.
Preferably, said jaws comprise cylindrical rollers, to facilitate rotation of said tubular whilst inhibiting axial movement thereof.
Advantageously, said apparatus comprises a lug for attachment to a pipe handling arm.
Preferably, said guide comprises a clamp.
The present invention also provides a pipe handling arm provided with an apparatus in accordance with the present invention.
The present invention also provides a method of handling a tubular to be connected to another tubular, which method comprises the steps of:
gripping said tubular with an apparatus in accordance with the present invention, and
using said apparatus to align said tubular with said another tubular.